本碩論提出一種具鎖相迴路控制之LLC諧振式直流電源轉換器，係利用鎖相控制技術使電路開關之操作頻率能自動追隨LLC諧振槽的諧振頻率進而調節開關之操作頻率，以獲致所需之電壓增益。
由於LLC諧振式直流電源轉換器上的LLC諧振槽與輸出負載之元件參數變動量會造成LLC諧振槽的電壓增益特性變異，致使定頻控制與傳統之變頻控制均無法精確地控制操作頻率，以獲得所需之LLC諧振槽電壓增益，甚至使電路開關之操作頻率低於諧振頻率，增加開關之切換損失。
因此，本論文提出鎖相控制之技術，藉由鎖定LLC諧振槽輸入電壓與變壓器二次側輸出電壓之相位訊號，使得操作頻率能夠自動追隨諧振頻率，並以此諧振頻率為基準，進而調節操作頻率，以達到所需之LLC諧振槽電壓增益。本論文將使用數學軟體Mathcad對雛型電路的LLC諧振槽進行特性分析與參數設計，並利用電路模擬軟體SIMPLIS對LLC諧振式直流電源轉換器進行系統分析與補償器設計以確保電路系統的穩定度。
最後本文將設計及完成一個200W的具鎖相迴路控制之諧振式直流電源轉換器，俾以驗證本論文所提出之直流電源轉換器的性能與可行性。

This thesis proposes a capacitively loaded loop (LLC) DC/DC resonant converter with phase-locked loop (PLL) control scheme. The PLL control scheme enables the switching frequency of the converter to continuously track the resonant frequency of the LLC resonant tank, which means the switching frequency is adjusted in order to obtain the required voltage gain.
Due to variations in the parameters of the LLC DC/DC resonant converter, including the LLC resonant tank and the output resistance, the voltage-gain characteristic of the LLC resonant tank is changed; this causes the fixed- and conventional variable-frequency controls to inexactly regulate the switching frequency in an attempt to obtain the required voltage gain. Therefore, the converter’s switching frequency will be lower than the resonant frequency of the LLC resonant tank, which results in an increase in switching loss.
Thus, this thesis presents a PLL control scheme, the use of which makes the switching frequency of the converter continuously track the resonant frequency of the LLC resonant tank by detecting the phase signals of the input and transformer secondary output voltages of the LLC resonant tank. Based on this resonant frequency, the switching frequency is adjusted to obtain the required voltage gain. In this thesis, the mathematic software Mathcad is used to complete the characteristic analysis and the parameters design of the LLC resonant tank. Meanwhile, the simulation software SIMPLIS is utilized to complete the system analysis and the compensator design of the LLC DC/DC resonant converter in order to ensure overall system stability.
The proposed 200W LLC DC/DC resonant converter with PLL control scheme is then designed and implemented to validate and demonstrate the performance and feasibility of the proposed DC/DC converter.

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